1. Field of the Invention
Steam turbines must cope with particulate material which passes through the stages and is capable of causing considerable harm. Particulate material can originate outside the turbine, such as boiler tube scale or weld beads and slag, or it can result from loose turbine pieces therewithin.
Such material can cause impaired turbine performance when permitted to penetrate into the horizontal Joints of diaphragms and shells or into the seal surfaces between diaphragms and shells. Such penetration is frequently found in turbines. It results primarily from the centrifugal effects of the whirling steam and rotating buckets which causes the particulate material to be thrown into the space between the diaphragm outer rings and the shells.
Such material can cause damage to nozzles and buckets as it passes through the turbine stages.
2. Description of Related Art
Turbine designers have not provided a significant protection system to minimize such damage. While manufacturers have provided protection for nozzles and bucket surfaces, little or nothing has been done to protect the components to which this invention is directed.